Alternatingly stacked thin film electrodes-based compact aqueous hybrid electrochemical capacitors for hundred-volts AC line filtering

Filtering capacitor with compact configuration and a wide range of operating voltage has been attracting increasing attention for the smooth conversion of the electric signal in modern circuits.Lossless integration of capacitor units can be regarded as one of the efficient ways to achieve a wider voltage range,which has not yet been fully conquered due to the lack of rational designs of the electrode structure and integration technology.This study presents an alternatingly stacked assemble technology to conveniently fabricate compact aqueous hybrid integrated filtering capacitors on a large scale,in which a unit consists of rGO/MXene composite film as a negative electrode and PEDOT:PSS based film as a positive electrode.Benefiting from the synergistic effect of rGO and MXene components,and morphological characteristics of PEDOT:PSS,the capacitor unit exhibits outstanding AC line filtering with a large areal specific energy density of 1,015 μF V^(2)cm^(-2)(0.28 μW h cm^(-2)) at 120 Hz.After rational integration,the assembled capacitors present compact/lightweight configuration and lossless frequency response,as reflected by almost constant resistor-capacitor time constant of 0.2 ms and dissipation factor of 15% at120 Hz,identical to those of the single capacitor unit.Apart from standing alone steadily on a flower,a small volume(only 8.1 cm^(3)) of the integrated capacitor with 70 units connected in series achieves hundred-volts alternating current line filtering,which is superior to most reported filtering capacitors with sandwich configuration.This study provides insight into the fabrication and application of compact/ultralight filtering capacitors with lossless frequency response,and a wide range of operating voltage.

Target slinging of droplets with a flexible cantilever

Control of the directional bounce of droplets impacting solid surfaces is crucial for many agricultural and industrial applications.However,for the universal impact process of raindrops on plant leaves,little is known about how the highly coupled and complicated fluid–structure interaction controls the postimpact motion of droplets and endows the leaves with tenacious vitality.Here,we report a leaf-like superhydrophobic cantilever to flexibly bounce droplets with well-defined directionality and controllability.Through theoretical modeling and three-dimensional fluid–solid coupling simulations,we find that the flexible cantilever significantly relieves the impacting forces of raindrops to reduce droplet fragmentation and enhance water repellency.The results further uncover the scaling relations of the droplet bouncing direction with respect to Weber number and cantilever stiffness.By this technique,the seemed disorganized postimpact movements of droplets are programmable and predictable,achieving the goal of where to point and where to hit automatically.This work advances the understanding of natural droplet impact phenomena,opens a new avenue for delicately controlling liquid motion in space with soft materials,and inspires a plethora of applications like soft robots to transport materials and energies,monitor plant growth as well as predict pathogen transmission in plants.